Improving basic relationships of pipe hydraulics

This communication presents the approaches set up for processing spinner flowmeter well logs in vertical wells with a single fluid phase, which is the most widely used in assessing wells productivity. These focus on improving the pipe hydraulics relationships so that the different fluid inputs throughout the well can be quantified. Since vertical flow inside wells varies with depth between laminar flows (very low Reynolds number, i.e. Re < 10³) and turbulent (Re > 4·10³) the aim has been to reduce the uncertainty in the transition interval. Starting from bibliographical data and/or well-known formulas for laminar and for turbulent flow, several continuous relationships have been developed for any regime: 1) an expression for the radial distribution of velocity inside the pipeline (velocity profile) was developed. 2) A relationship between the average velocity and the velocity at the axis (velocity factor) was created. 3) A third equation was generated to obtain the friction factor in smooth pipes (and starting from this, a new explicit equation for rough pipes). The purpose has been to have a set of empirical expressions of easy and continuous application for any regime, as an alternative to the use of computer simulations.     

The cannibalization effect of wind and solar in the California wholesale electricity market

Increasing penetration of zero marginal cost variable renewable technologies cause the decline of wholesale electricity prices due to the merit-order effect. This causes a “cannibalization effect” through which increasing renewable technologies’ penetration undermines their own value. We calculate solar and wind daily unit revenues (generation weighted electricity prices) and value factors (unit revenues divided by average electricity prices) from hourly data of the day-ahead California wholesale electricity market (CAISO) for the period January 2013 to June 2017. We then perform a time series econometric analysis to test the absolute (unit revenues) and relative (value factors) cannibalization effect of solar and wind technologies, as well as the cross-cannibalization effects between technologies. We find both absolute and relative cannibalization effect for both solar and wind, but while wind penetration reduces the value factor of solar, solar penetration increases wind value factor, at least at high penetration and low consumption levels. We explore non-linearities and also find that the cannibalization effect is stronger at low consumption and high wind/solar penetration levels. This entails that wind and (mainly) solar competitiveness could be jeopardized unless additional mitigation measures such as storage, demand management or intercontinental interconnections are taken.     

巨型工程机械子午线轮胎高强度、低生热胎面基部胶配方开发

通过对国外知名品牌37.00R57和40.00R57规格巨型工程机械子午线轮胎胎面基部胶组成分析和物理性能测试,对我公司巨型工程机械子午线轮胎胎面基部胶配方进行优化设计。新开发配方半成品和成品胶料动态损耗因子分别降低37.9%和26.6%,胶料物理性能达到竞品水平,成品轮胎TKPH提升13.6%。     

Fucoidans as Potential Therapeutics for Age-Related Macular Degeneration—Current Evidence from In Vitro Research

Age-related macular degeneration (AMD) is the major reason for blindness in the industrialized world with limited treatment options. Important pathogenic pathways in AMD include oxidative stress and vascular endothelial growth factor (VEGF) secretion. Due to their bioactivities, fucoidans have recently been suggested as potential therapeutics. This review gives an overview of the recent developments in this field. Recent studies have characterized several fucoidans from different species, with different molecular characteristics and different extraction methods, in regard to their ability to reduce oxidative stress and inhibit VEGF in AMD-relevant in vitro systems. As shown in these studies, fucoidans exhibit a species dependency in their bioactivity. Additionally, molecular properties such as molecular weight and fucose content are important issues. Fucoidans from Saccharina latissima and Laminaria hyperborea were identified as the most promising candidates for further development. Further research is warranted to establish fucoidans as potential therapeutics for AMD.     

Click-Chemistry (CuAAC) Trimerization of an αvβ6 Integrin Targeting Ga-68-Peptide: Enhanced Contrast for in-Vivo PET Imaging of Human Lung Adenocarcinoma Xenografts

α_vβ₆ Integrin is an epithelial transmembrane protein that recognizes latency-associated peptide (LAP) and primarily activates transforming growth factor beta (TGF-β). It is overexpressed in carcinomas (most notably, pancreatic) and other conditions associated with α_vβ₆ integrin-dependent TGF-β dysregulation, such as fibrosis. We have designed a trimeric Ga-68-labeled TRAP conjugate of the α_vβ₆-specific cyclic pentapeptide SDM17 (cyclo[RGD-Chg-E]-CONH₂) to enhance α_vβ₆ integrin affinity as well as target-specific in-vivo uptake. Ga-68-TRAP(SDM17)₃ showed a 28-fold higher α_vβ₆ affinity than the corresponding monomer Ga-68-NOTA-SDM17 (IC₅₀ of 0.26 vs. 7.4 nM, respectively), a 13-fold higher IC₅₀-based selectivity over the related integrin α_vβ₈ (factors of 662 vs. 49), and a threefold higher tumor uptake (2.1 vs. 0.66 %ID/g) in biodistribution experiments with H2009 tumor-bearing SCID mice. The remarkably high tumor/organ ratios (tumor-to-blood 11.2; -to-liver 8.7; -to-pancreas 29.7) enabled high-contrast tumor delineation in PET images. We conclude that Ga-68-TRAP(SDM17)₃ holds promise for improved clinical PET diagnostics of carcinomas and fibrosis.     

Propagation and termination of an internal crack in continuously cast austenitic stainless steel analyzed by ∑ values and the Schmid factor

The formation mechanism of an internal crack was clarified from the viewpoint of the crystallography and thermal expansion. An inverse pole figure map obtained by EBSD pattern showed that the crack propagated along the grain boundaries having high ∑ values within the columnar zone. After the crack initiation, these positions were considered to undergo cracking followed by propagation toward the equiaxed side. Near the termination position, the grains ahead of crack propagation had a Schmid factor higher than 0.45 consuming elastic strain energy. Thermal expansion measurements showed that the grain with (0 0 1) orientation had the largest expansion while that with (0 1 1) the smallest. The grain boundaries neighboring the combination of (0 0 1) and (0 1 1) grains had the largest thermal stress. Therefore, thermal stress contributed to the initiation of cracking. It was thus proposed to enlarge the equiaxed zone to prevent cracking by discontinuing the crack propagation.     

A study on the thermoelectric properties of ALD-grown aluminum-doped tin oxide with respect to nanostructure modulations

The thermoelectric properties of aluminum-doped tin oxide (ATO) thin films synthesized by thermal atomic layer deposition (ALD) were studied with respect to the aluminum concentration. The overall aluminum content in each layer was modulated by adjusting the relative number of tin oxide (SnO₂) and aluminum oxide (Al₂O₃) growth cycles, where a sequential process involving n cycles of SnO₂ growth followed by 1 cycle of Al₂O₃ deposition was performed (building up a super-cycle). The electrical conductivity (620 S/cm), free carrier concentration (1.23x10²¹ cm^-3), and power factor (0.49 mW/K²m) increase until their maximum values are reached when the Al content is approximately 1.50 at% of the cations, and decrease as more Al is added in. On the other hand, the Seebeck coefficient decreases monotonically as the Al content increases up to about 2.88 at%, and begins to increase with further Al doping. Here the thermoelectric efficiency is therefore determined primarily by the free carrier concentration, while the Seebeck coefficient appears to be influenced by the overall crystal structure.     

Critical roles of the rhombohedral-phase inducers in morphotropic NaNbO3-BaTiO3-ABO3 quasi-ternary lead-free piezoelectric ceramics

A morphotropic phase boundary (MPB) between rhombohedral (R) and tetragonal (T) phases was identified in a few (0.9-x)NaNbO₃-0.1BaTiO₃-xABO₃ (x?=?0–0.05) lead-free systems. Critical roles of R-phase inducers were specially evaluated in terms of phase boundary position, microstructure and piezoelectric responses. The results indicate not only the tolerance factor of the ABO₃ additive but also its ferroelectricity and corresponding volume change would influence the formation of phase boundary and further determine dielectric and ferroelectric responses. The piezoelectric coefficient d₃₃ of MPB compositions was compared with theoretically-calculated d_33-cal according to d₃₃?=?2P_r·ε₃₃·Q₃₃, demonstrating that the piezoelectric response of these systems should be determined by combined effects of the phase coexistence, nano-scale domains and particularly enhanced dielectric responses. The largest d₃₃ ～305 pC/N, the highest ε₃₃^T/ε_o ～2815 and the lowest P_r ～14.7 μC/cm² were achieved in the MPB composition with 3.75% SrZrO₃. These experimental results provide a valuable reference for designing new NaNbO₃-based lead-free piezoelectric materials.     

Structure,stability and permeation properties of NaA zeolite membranes for H2O/H2 and CH3OH/H2 separations

NaA zeolite membranes were synthesised in the secondary growth hydrothermal method based on the seeding of the inner surface of a ceramic α-alumina tube. The impacts of crystallisation time and zeolite precursor concentration (in H₂O) were investigated. The structure and stability of the prepared NaA zeolite membranes were also investigated with operating temperatures, times and pressures. The results indicate that the optimal synthesis gel molar composition was 3Na₂O: 2SiO₂: Al₂O₃: 200H₂O. This led to cubic-shaped NaA zeolite which showed good stability. The optimal NaA zeolite membrane had H₂O and CH₃OH fluxes of 2.77 and 0.19 kg/m²h, with H₂O/H₂ and CH₃OH/H₂ separation factors of ∞ and 0.09 at a temperature of 30 °C. The NaA zeolite membrane had high thermal stability, but poor separation performance at high temperature (240 °C). The results suggested that the H₂ permeation flux is significantly influenced by preferential adsorption of vapour in the NaA zeolite membrane.     

钢轨交流闪光焊接过程过梁爆破特征分析

以高速摄影技术作为主要研究手段，研究钢轨交流闪光焊接过程过梁爆破特征，并结合热成像系统采集焊接过程温度场，以此为数据基础定量分析了钢轨交流闪光焊接过梁爆破特征. 结果表明,钢轨交流脉动闪光焊接工艺模式下，加速闪光阶段具有几个阶段中最高的闪光频次46.93次/s，脉动闪光阶段具有最低的闪光频次11.07次/s；连续闪光阶段闪光烈度为0.009 2 mm/次，是几个阶段中最强的，脉动阶段的闪光烈度最弱，为0.003 8 mm/次；从闪光加热因子来看，脉动阶段最高，符合了该阶段积累热量的主要目的；加速闪光阶段最低，是由于该阶段为了制造保护气氛产生的气化过梁带走了较多的热量；从闪光均匀度看，闪光最不均匀的阶段是闪平阶段，最均匀的阶段是脉动阶段，这恰恰说明了两待焊端面的微观平行情况在闪平阶段最差、脉动阶段最佳.